IL38575A - Method and apparatus for indicating the passing of a projectile through an area in space - Google Patents

Description

38575/2 This invention relates to indicating the passing of a projectile through an area in space* The Invention has particular application in determining accuracy of aim of bullets, cannon shells, missiles and the like at a target and has particular application in air-to-air and air-to-ground gunnery.

Hitherto it has been necessary to visually inspect towed drogue targets after shooting thereat by an attacking aircraft* The count of hits determined by that inspection can then be radioed to the attacking aircraft. The time taken for the visual inspection is considerable and as we are here considering military aircraft which are expensive to keep in the air the cost of the visual inspection is considerable.

The object of this Invention is to provide a method of, and apparatus for, indicating the passing of a projectile through a target area In space which can be applied to gunnery generally and speci ically, but not exclusively, to air-to-air and air-to-ground gunnery.

The present invention provides a method of Indicating the passing of a gunnery projectile through an area in space comprising projecting a continuous light beam to illuminate the whole of said area and detecting a reflection of said beam from a gunnery projectile passing through said area resulting from incidence of said beam thereon thereby determining that said projectile passed through said area and wherein said beam is of a size, in use, insufficient to Illuminate the whole of said area but is scanned such that said beam illuminates the whole at sad am will illuminate a 38575/2 There is also provided in accordance with an embodiment of the invention a method of indicating the passing of a gunnery projectile through an area in space comprising projecting a stationary continuous light beam to illuminate the whole of said area and detecting a reflection of said beam rom a gunnery projectile passing through said area resulting from incidence of said beam thereon thereby determining that said projectile passed through said area and including the step of disregarding reflections of said beam from a gunnery projectile having magnitudes above and below predetermined magnitudes to define boundaries of said area.

Further in accordance with an embodiment of the invention there is provided a gunnery projectile detecting apparatus, comprising a light beam projector adapted to illuminate the whole of an area in space with a continuously projected light beam and a detector adapted to detect a reflection of said beam from a gunnery projectile passing through said area resulting from incidence of said beam thereon to determine that said gunnery projectile passed through said area and wherein said projector is such that said beam is of a size which, when in use, is insufficient to Illuminate the whole of said area and including scanning means adapted to scan said beam such that said beam illuminates the whole of said area and such that said beam will illuminat a gunnery projectile passing through said area.

Preferred aspects and details of the present Invention will now be described with the aid of the accompanying drawings In which: Figure 1 is a schematic representatio of an optical part of an apparatus in accordance with the present invention.

Figure 2 is a schematic representation of a different version of the optical par of the apparatus shown in Figure 1.

Figure 3 is a perspective view of a lens used in the apparatus show in Figure 1.

Figure 4 is a perspective view of a reflector used in the apparatus shown in Figure 2.

Figure 5 is an end view of the reflector shown in Figure 4.

Figure 6 is a representation of an area incided with light by the apparatus shown in Figures 1 and 2.

Figures 7, 8 and 9 are block circuit diagrams of apparatus forming an electronic part of the present invention.

Figure 10 is a cross sectional view of a bird and drogue in which bird the apparatus shown in Figure 1 and 2 may be fitted and towed behind an aeroplane.

Referring to Figure 1 the optical part of the apparatus has a continuous wave helium-neon laser 1.

A beam 2 generated by the laser 1 is directed onto an inclined quartz mirror 3 which has a mirror coating on the second surface, relative to beam 2 , such that between 95% to 99% of beam 2 is transmitted therethrough to be beam 4. Beam 4 is passed into a lens 5. The lens 5 is shaped as a segment of a circle cut from a sheet of angle of the segment and passes centrally thereinto at a circular cut-out portion 6. Cut-out portion 6 causes beam 4 to project as beam 8 which can for convenience be called "the incident beam" which is of substantially rectangular g%oaa section as shown by dotted line without substantial transverse divergence.

If a projectile such as a bullet or canno shell should pass through beam 8 it will be inclded by beam 8.

Since the projectile cannot be a perfect black body, a portio of the beam will be reflected thereby/ and a portion of that reflection conveniently known as "the reflected beam" , will return to lens 5 where it will be collected and directed at mirror 3 as beam 9. Beam 9 will reflect off mirror 3 which is first surface coated, with respect thereto, as beam 10. The coating of mirror 3 is such that beam 10 will be between 95% - 99% of beam 9. Beam 10 passes through an optical band pass filter 12 which prevents light of frequency substantially different to that o laser 1 from passing - so as to reduc errors which ma arise from stray light such as sunlight. Beam 10 passes as beam 13 which then passes through lens 14 which focuses beam; 13 onto the centre o PIN diode 15. PIH diode 15 thus emits an electrical signal represented as 17. Signal 17 will be hereinafte referred to as the reflected signal. The optical part of the apparatus described with respect to Figure 1 provides a indication of a projectile passing through beam 8 can bp used, as to be described later, to give an indication of accuracy of shooting at a target* As lens 5 is shaped primaril for projecting beam 4 as beam 8 and not for receiving the reflected beam off a projectile and causing that beam to be. beam 9 a= further lens 38575/2 shaped primarily for receiving the reflected beam may be provided and placed at a suitable location adjacent lens 5 to receive a reflected beam when it reflects along an axis to one side of the axis of projecting beam 8.

Referring now to Figure 2, which shows a different version of an optical part of the apparatus, there is provided a helium-neon laser 21 which generates a continuous wave laser beam 22. The beam 22 generated by the lase is directed onto an inclined quartz mirror 23 first surface coated, relative to beam 22, which has a mirror coating such that between 1 and 5% of the beam 22 is reflected thereby to be beam 24 and between 95% and 99% of the beam 2 passes therethrough to be beam 26.

Beam 26 is directed onto an inclined quartz mirror 27 second surface coated, relative to beam 26, and substantially all of beam 26 passes therethrough to be beam 28.

Beam 28 then passes to a faceted reflector 29 and is reflected thereby to be beam 31.

The reflector 29 comprises a rectangular body 32 which is rotated about a face centred axis on shaft 33 by motor 34. Also fixed to the shaft is a disc 36. On the body 32, see Figures 4 and 5, are four planar mirro surfaces. The mirrors are disposed at 90° relative to one another on the sides of the body 32.

It is to be noted that said axis is at right angles to beam 28 but for convenience of depiction is shown in line therewith in Figure 2.

Prior to passing to body 32 beam 28 is passed through a lens 5 similar to that described in respect of As a result of rotation of the body 32 the beam 28 is reflected, in turn, by each of the mirrors to be, as stated before, beam 31. Beam 31 as a result of rotation of the body 32 scans an area, hereinafter called "the scanned area". The scanned area has the shape shown in Figure 6.

As a result of lens 5 the beam 31 has an elongated section 37 as shown in Figure 2 and Figure 6.

The shape of the scanned are is as shown in Figure 6 and the reflector causes beam 31 to be of elongated section 37 as aforesaid and outwardly diverging as shown and scanning a segment. A lower limit as far as operation of the apparatus is concerned is arbitrarily set and an upper limit as far as operation of the apparatus is concerned is arbitrarily set in an electronic part of the invention.

The depth of the beam to a projectile at the lower limit of scan is conveniently 27 inches.

The angular velocity of the body 32 and the width of the beam 31 (measured along the long and short axes of said elongated section 37) are chosen so that a projectile such as a bullet passing through the scanned area will be incided by beam 31.

For a projectil speed of 4000 ft/sec. the time to travel through the beam, for the depth of the beam to the projectile of 27 inches at the lower limit of intended scan 27 » ^g- m.sec » 0.564 m.sec* Thus for a 4 sided body 32 the speed of rotation of the body 32 is desirably not less than ¾ 5%4 χ β 440 Revs/sec » 27600 RPM. In practise we have found it best for these dimensions to be in excess of that required so as to be applicable to a wide range of projectile velocities. 38575/2 If a projectile such as a bullet or cannon shS-Tl should pass through the scanned area it will be incided by the beam 31. Beam 31 is conveniently called "the incident beam". Since the projectile cannot be a perfect black body, beam 31 will be reflected thereby and a portion of the reflectio will travel back along the path of beam 31 at the instant of incidence. That portion will be known as beam 38 and it is convenient to refer to it as "the reflected beam" and it will be realised that the beam 38 will have the nature of a pulse and not be continuous.

Beam 38 is reflected by the mirrors on body 32 and will travel along the path of beam 28, except tha it will travel in the opposite direction/ as beam 39.

Beam 39 meets mirror 27 which, to beam 39 is first surface coated, and is substantially entirely reflected thereby as bea 41.

Beam 41 then passes to optical band pass filter 42 which prevents ■ light of frequency substantially different to that of the laser, fro passing - so as to reduce errors which may arise from. stray light such as sunlight.

From filter 42 beam 43 emerges and passes to a PIN diode 44. The beam 43 causes the diode 44 to emit an electrical signal which is represented as 46. That signal will be hereinafter called "the reflected signal".

Beam 24 is passed to inclined mirror 47 and is substantially entirely re lected thereby to be beam 48.

Beam 48 passes through lens system 49 and emerges as beam 51.

The disc 36 has a large number of holes adjacent its peripher with their centres at the same radial distance from the centre of rotation of the disc. The holes are arranged i four groups and the groups are angularly disposed 3Θ575/2 beam 38 the group corresponding to that mirror is disposed so that beam 51 is passing through the holes in that group to emerge from the disc as pulse beams 52.

Pulse beams 52 pass to PIN diode 53 and cause the diode 53 to emit a pulsed electric signal which is represented as 5 * That signal will be hereinafter called "the reference pulse signal*1.

In use the apparatus is set up so that the scanned area will be in front of a target or other convenient objects to aim at. The invention, of course, has particular application in air-to-air and air-to-ground gunnery and in which case the scanned area will be in front of a towed drogue as show i Figure 10, or behind a towed drogue or in ront of or behind a ground target.

Referring now to Figure 10, when the apparatus is to be used in air-to-air gunnery a bird 60 is connected at one end by a tow line 61 to an aircraft and connected at the other end by a tow line 62 to a drogue 63. The optical part of the invention is show as a block 64 and is arranged such that the incident beam produced by it is in a vertical plane adjacent drogue 63.

If the optical part of the apparatus as described with respect to Figure 1 is sued in the bird 60 then the lens 5 thereof is arranged so that the incident beam thereof is as shown by lines 66-67.

If the optical part of the apparatus as shown in Figure 2 is used in the bird 60 the mirror surfaces can be arranged to cause the angle of scan of the beam to be as shown by lines 66-67 but preferably they are arranged to cause the scan to be as shown between lines 68-69 and with a minimum and maximum ranges as show with respect to the drogue 63. 38575/2 At the end of a days shooting the drogue 60 can foe hauled In. to the aircraft or the tow line 61 can be released from the aircraft and parachute In the bird 60 made operable as a consequence of releasing towline 61 so that the bird can be safely landed.

It will be realised that the optical part of the apparatus can be mounted In the aircraft Instead of in the bird for air-to-air gunnery but because the drogue is towed a considerable distance behind the aircraft so as to avoid the towing aircraft from being hit by projectiles and for economy of laser constructions and efficiency of operation of the apparatus we prefer the optical part of the apparatus to be as close as possible to the target so the magnitude of reflection of the laser beam will be as large as possible.

In air-to-ground gunnery the optical part of the apparatus is arranged to produce the incident beam in front of the target as is shown in Figure 6.

Manners in which the reflected signal and the reference pulse signal can be used will now be generally described and thereafter circuitry used to derive information from those signals will be described in detail.

Since the reflected signal is a pulsed signal the numbe of projectiles passing through the scanned area is determined merely by counting the pulses. By this means a crude estimation of aim accuracy is obtainable.

Further, since the reflected signal will have a magnitude related to the magnitude of the reflected beam and, since the magnitude of the reflected beam is related to the .. distance of the projectile on which the incident beam inclded, it is possible, by rejecting signals of below or above 38575/2 on the range at which projectiles will be detected. These ranges are shown in Figures 6 and 10. It will be realised that this provides a better estimating of aim accuracy. Further increase in quality of estimation can be obtained by determining the relation of the magnitude of the reflected signal to range of projectiles but it will be realised that such a relation is likely to vary substantially dependent on whether the reflected signal is obtained from relatively large or relatively small calibre projectiles.

By the use of the optical part of the apparatus as shown in Figure 2 with the aid of other means possible to determine the angular position, relative to an imaginary baseline, of a detected projectile in the scanned area. This is done by providing a certain aperture in said disc larger than the other apertures. Said certain aperture will produce a pulse in the reference pulse signal larger than the pulse produced by the other apertures. Said certai aperture is also positioned so that the pulse produced thereby is produced at the instant that one of the mirrors commences to scan the scanned area.

By knowing the number of pulses produced during the time that said one of the mirrors is scanning the scanned area and by dividing that number by another anumber - conveniently, three -it is possible, b counting pulses and relating the reflected signal to the count at the time that the reflected signal is received to determine the angular position, relative to an imaginary base line, of a projectile In the scanned area i three segments of the scanned area. Thus an even more accurate estimation of aim accuracy is obtained.

The above is a general description of manners of using the pulse reference signal and the reflected signal. More s ecific details and circuitr used in a referred instance is 38575/2 The circuit used for obtaining signals corresponding to a projectile passing within a certain range of the origin of the incident beam is shown in Figure 7 and includes a PIN diode (previously referred to by number as 15 and 4) .

JShen a reflected lig^t|beam off a? projectile strikes PIN diode a signal is generated which is now indicated by 100. The signal 100 is fed to a band pass ilter B.P.F. arranged with circuit constants to only allow a signal falling within a predetermined range o amplitude and duration to pass. The signal passed from the band pass filter is shown generally as 102· The signal 102 is ampli ied by a radio frequency amplifier R.F, and clamped by a level set and detector to have a suitable shape shown generally as 103* The signal 103 is used to trigger an oscillator to generate a signal, shown generally as 104 of known duration and amplitude. A D.C. regulator is sed for supplying constant voltage to the above circuit integers.

When using the optical part of the apparatus as shown in Figure 1 th signal 104 can be fed di ec ly into a store. This is shown basically in Figure 8 except that additional circuitry outlined with dotted lines is shown. The additional circuitry will be explained later. On the receiver REC receiving a command signal the STORE is made operative to feed information stored therein in binary code on signals from CLOCK concerning hits to a transmitter TRANS which In turn transmits the information to be received by an aircraft firing at the drogue or ground target. The transmitter TRANS operates at a frequency such that the usual NAV/COMM equipment in the aeroplane can receive the information. This is basically shown in Figure 9 except that further additional circuitry is shown. The further additional circuitry will be explained later. unit DISPLAY which has a series of digital reading display tubes for giving an indication of the numbe of projectiles which passed through the inciden beam and hence the number of target hits.

The receiver REC in the circuitry shown in Figure 8 is made operative on receipt of a command signa from the transmitter in the NAV/CQMM equipment of the aircraft which is shooting at the target. he command signal ca be initiated by the pilot or gunner in the aircraft.

When the optical apparatus shown in Figure 2 is used the signal 104 is pref rably fed to three electronic gates, AND 1, AND 2 and AND 3, (see Figur 8) which gates are "; individuall openable for a period corresponding to a number of selected reference pulse signals* The selected reference pulse signals are obtained by providing suitable dividing means for dividing the pulse signals generated b the number of apertures in the disc 36 into groups of signals and using those signals to operate further circuit mean to generate a signal to open a gate for the duration of each group of signals. The disc 16 has 1,199 equally spaced circumferential apertures and one larger circumferential aperture, totalling 1200 apertures. The larger aperture is aligned to correspond to the start of scan of th beam across the scanned area by one of th -mirrors. Because ther-are four mirrors there are —2. » 300 apertures corresponding to each mirror. By providing dividing means for countin m> loo pulses and means for generating a signal to be fed to one of the three gates for the duration of 100 pulses and, to a second of the three gates for the duration of the next 100 pulses and, to a third of the three gates for the duratio of 100 pulses from the SYNC and back to the said on of the gates for the next 100 pulses, etc. , we can open each of the gates for a third 38575/2 ^ the area of scan is divided into three sectors. As the ignal 10 is fed to all three gates, it passe only through the gate which is opened* Hence we can obtain a signal representative of which sector a projectile passed through, and hence we can obtain a more accurate determinatio of the accuracy of the aim of the projectile. The three gates may correspond to "Left of target", "Hit target", and "light of target" respectively. The hit information from the gates is fed into the STORE and transmitted as described for the optical construction shown in Figure 1.

The hit information transmitted by TRANS is received by the NAV/CGMM equipment shown in Figur 9 and fed into a STORE from the STORE the information is fed to a decode which decodes the informatio which is in binary form into a suitable form for operating a display unit. The decoded information is fed to a display unit DISPLAY where it can be read by an observer.

It will b appreciate that by using the apparatus as described above it is possible for a number of aircraft to fire at a target, one at a time., and for an indication of th accuracy of shooting at the target to be given almost instantaneously. Hence the cost of keeping several aircraft in flight, whilst manually counting the hits of the target is reduced.

In order to eliminate the effect of sunlight or effects of other light beams or effects of slow moving objects passing through the incident beam from being registered as hits the circuitry used for registering a hit resulting from a projectile passin through the incident beam may be arranged to operate when a projectile leaves th scanned area, b 38575/2 In order to reduce the diameter of disc 36 having regard to the problems involved, in producing a required number of apertures at the periphery thereof as the disc becomes smaller and smaller In diameter th disc can be provided with magnetic signals of differing frequency and having a relation to the number of apertures which would otherwise be used. A tape recording replay head can be arranged to read the recorded signals as the disc 36 rotates so that signal 54 can be generated and used as previously described.

To ensure that a hit is not registered in two sectors of scan if a projectile passes through the transition position of two adjacent sectors of scan/ the reflected signal can be used to inhibit the next count until, after a set time.

Throughout the specification the term light beam has been. used and this is to be understood to include light which is visible and light which Is not visible, The term "light beam0 is to include light which is in the I.R. spectrum and light which Is in tixe U.V. spectrum.

Claims (38)

38575/2

1. A method of indicating the passing of a gunnery projectile through an area in space comprising projecting a continuous light beam to illuminate the whole of said area and detecting a reflection of said beam from a gunnery projectile passing through said area resulting from incidence of said beam thereon thereby determining that said projectile passed through said area and wherein said beam is of a size, in use, insufficient to illuminate the whole of said area , but is scanned such that said beam illuminates the whole of said area and such that said beam will illuminate a gunnery projectile passing through said area.

2. A method as claimed in claim 1 wherein said beam is fan shaped in a plane generally parallel with the intended firecti on of travel of the gunnery projectile.

3. A method as claimed in any one of the preceding claims, wherein said reflection is one directed substantially along the axis of incidence of light on said gunnery projectile.

4. A method as claimed in any preceding claim, wherein said reflection is used to generate an electrical signal.

5. A method as clatned in claim , wherein said electrical signal is used to produce a visual or audible signal.

6. A method as claimed in claim 4, wherein said signal and similar signals consequent on said beam illuminating other gunnery projectiles are stored in and are retrievable from a store to indicate the number of gunnery projectiles which passed through said area.

7. A method as claimed in any one of the preceding claims wherein said beam is produced by directing light from a source onto a reflecting member which, when in use, is moving.

8. Λ method as claimed in any one of the preceding claims and including the step of relating said reflection to the angular position of said beam at the time of detecting said reflection whereby information is derived on the angular position of said gunnery projectile.

9. A method as claimed in any one of the preceding claims, and including the step of disregarding reflections of said beam from a gunnery projectile having magnitudes above and below predetermined magnitudes to define boundaries of said area.

10. A method of indicating the passing of a gunnery projectile through an area in space comprising projecting a stationary continuous light beam to illuminate the whole of said area and detecting a reflection of said beam from a gunnery projectile passing through said area resulting from Incidence of said beam thereon thereby determining that said projectile passed through said area and including the step of disregarding reflections of said beam from a gunnery \ projectile having magnitudes above and below predetermined magnitudes to define boundaries of said area.

11. A method as claimed in claim 10, wherein said beam is fan shaped and the plane of said beam substantially parallel to said area. 38575/3

12. A method as claimed in claim 10 or claim 11 wherein said reflection is one directed substantially along the axis of incidence of light on said gunnery projectile.

13. A method as claimed in any one of claims 10 to 12 wherein said reflection is used to generate an electrical signal.

14. Λ method as claimed in claim 13, wherein said electrical signal is used to produce a visual or audible signal.

15. A method as claimed in claim 13, wherein said signal and similar signals consequent on said beam illuminating other gunnery projectiles are stored in and are retrievable from a store to indicate the number of gunnery projectiles which passed through said area.

16. A method as claimed in any one of the preceding claims wherein said area in space includes a plurality of sisaller areas in space and determining vhich of said smaller areas the gunnery projectile passed through by determining which of said smaller areas the reflection originated from. 38575/3

17. · A gunnery projectile detecting apparatus, comprising a light beam projector adapted to illuminat the whole of an area in space with a continuously projected light beam and a detector adapted to detect a reflection of said beam from a gunnery projectile passing through said area resulting from incidence of said beam thereon to determine that said gunnery projectile passed through said area and wherein said projector is such that said beam is of a size which, when in use, is insufficient to illuminate the whole of said area and including scanning means adapted to scan said beam such that said beam illuminates the whole of said area and such that said beam will illuminate a gunnery projectile passing through said area.

18. Apparatus as claimed in claim 17 wherein said projector includes a movable reflector on which light from a light beam source, in use, is directed,

19. Apparatus as claimed in claim 17 or 18 wherein the detector is adapted to detect substantially only reflections from said gunnery projectile directed substantially along the axis of incidence of light on said projectile.

20. Apparatus as claimed in any one of claims 17 to 1 , wherein said projector is such that said beam is fan shaped in a plane generally parallel with the intended direction of travel o the unner ro ectile. 38575/ 3~

21. Apparatus as claimed in any one of claims 17 to 20, and including means adapted to produce a visual or audible signal on detection of said reflection by said detector.

22. Apparatus as claimed in any one of claims 17 to 21 and including means adapted to relate said reflection to the angular position of said beam at the time of detecting said reflection by said detector to provide information on the angualar position of said gunnery projectile.

23. Apparatus as claimed in any one of claims 17 to 22 and including means adapted to .. disregard reflections of said beam from a gunnery projectile having magnitudes above and below predetermined magnitudes to define boundaries of said area. 2k.

24. Apparatus as claimed in any one of claims 17 to 23» wherein said detector is adapted to , produce an electrical signal on detection of said reflection.

25. Apparatus as claimed in claim 2k and including an information store adapted to store said signal and similar signals resulting from incidence of said beam on other gunnery projectiles and to produce those signals from store on commend.

26. A gunnery projectile detecting apparatus, comprising a light beam projector adapted to illuminate the whole of an area in space with a continuously projected stationary light 38575/ 3 beam and a detector adapted to detect a reflection ^ of said beam from a gunnery pro jectile passing through said area resulting from incidence of said beam thereon to determine tha t said gunnery projectile passed through said area and including means adapted to disregard reflections of said beam from a gunnery projectile having magnitudes above and below predetermined magnitudes to define boundaries of said area.

27. . A gunnery projectile detecting apparatus as claimed in claim 26 , and including a light beam source adapted to produce light to be projected as said beam by said projector.

28. Apparatus as claimed in claim 26 or claim 27 wherein the detector is adapted to detect substantially only reflections from said gunnery projectile directed substantially along the axis of incidence of light on said projectile.

29. Apparatus as claimed in any one of claims 26 to 28, wherein said projector is such tha t said beam is fan shaped and the plane of said beam is parallel to the plane of the area.

30. . Apparatus as claimed in any one of claim 26 to 29 » wherein said detector is adapted to produce an electrical signal on detection of said reflection.

31. . Apparatus as claimed in claim 30 and including an information store adapted to store said signal and similar signals resulting from incidence of said beam on other gunnery projectiles and to produce those signals from store on command. 38575/3

32. Apparatus as claimed in any one of claims 17 to 31 therei said area in space includes a plurality of smaller areas in space and determining means for determining which of said areas said reflections originated from.

33. Gunnery apparatus as claimed in claim 32 and including means adapted to produce an electrical signal consequent on detection of said reflection, means adapted to produce an electrical reference signal representative of the one of said areas being scanned by said beam at any one time and Including means adapted to relate the first mentioned signal to the electrical reference signal to provide an indication of which of said areas said projectile passed through.

34. Gunnery apparatus as claimed in claim 33, and including said number of electronic gates selectively operable by the electrical reference signal whereby each of said gates represents one of said areas and Is open when said beam is scanning the respective one of said areas and wherein circuitry is provided adapted to feed the first mentioned electrical signal to said gates whereby passage of the first mentioned electrical signal through one of said gates indicates which of said areas said projectile passed through.

35. Gunnery apparatus as claimed in claim 34 and including transmitting means adapted to transmit the electric signals which pass said gates after coding by coding means to a receiver having a decoder adapted to decode and a display adapted to displa the number of projectiles which passed through each of said areas. 38575/3

36. Gunnery apparatus as claimed in claim 34 , -including a circuit adapted to, in use, generate a further electrical signal of knovm amplitude and duration on receipt of the first mentioned electrical signal and wherein said further electrical signal is adapted to operate circuitry for providing a display of a projectile passing through the said area.

37. Gunnery apparatus substantially as shown and described hereinabove.

38. Gunnery apparatus substantially as shown and described in the drawing. SC:CB